Determining levels of arousal using electrocardiography: A study of HRV during transcranial magnetic stimulation

Introduction. Electrocardiography (ECG) can be used to collect heart rate data which in turn can be used to measure heart rate variability (HRV). The sympathetic and parasympathetic nervous systems have the ability to affect this variability, which can ultimately affect arousal levels. Background. This study was designed to determine if changes to HRV can be detected while subjects undergo transcranial magnetic stimulation (TMS), and if these changes are from decreased arousal. Methods. LabChart™ software was utilized to collect and analyze initial heart rate data to generate R-R intervals. Further analysis was then performed in order to determine RRV3 and RRV8-3. Results. Low arousal levels were detected in 5 of the 6 analyses, demonstrating that the subjects' arousal levels changed throughout the experiment. Conclusion. HRV effectively measures arousal levels. Future research should be done involving continuous collection of heart rate during TMS to allow for a cross comparison between time of low arousal states and potential changes to TMS data.